PB2534: SARS-COV-2 IMMUNIZATION AFTER VACCINES IN PATIENTS WITH HEMOGLOBINOPATHY: A SINGLE CENTER EXPERIENCE
Authors: Andrea Duminuco, Anna Bulla, Rosamaria Rosso, Marina Romeo, Cambria Daniela, Enrico La Spina, Benedetta Ximenes, Cesarina Giallongo, Daniele Tibullo, Alessandra Romano, Francesco DI Raimondo, Giuseppe Palumbo
Journal: HemaSphere (2023)

Topic: 27. Thalassemias Background: Hemoglobinopathies are a heterogeneous group of inherited disorders characterized by alterations in hemoglobin synthesis. Immune system status of these patients is known to be altered due to underlying pathophysiological mechanisms of the disease, such as ineffective erythropoiesis (IE), chronic haemolysis and anemia, multiple blood transfusions, deferoxamine therapy, iron overload and tissue hypoxia. Starting from these assumptions, during the SARS-CoV-19 pandemic, these patients were considered as vulnerable, with no certainty of possibly being able to respond adequately with the production of antibodies. To our knowledge, real-life data on immunization with SARS-CoV-2 vaccines in patients with thalassemia and sickle cell disease are few. Aims: This study aims to describe our Center experience assessing the level of protective antibodies against SARS-CoV-2 developed by patients affected by hemoglobinopathies after SARS-CoV-2 virus mRNA vaccine vaccination. Methods: Our cohort was based on 114 adult (>18 years) patients affected by hemoglobinopathies, 88 transfusion-dependent and underwent two doses of vaccination for SARS-CoV-2, without noteworthy side effects. 98 patients were affected by β-thalassaemia (63 thalassaemia major and 35 thalassemia intermedia, 88 of which were transfusion-dependent), 10 by combined forms of thalassaemia (such as β-thalassaemia/HbE and α-thalassaemia), 2 homozygous sickle cell anemia, and 14 thalasso-drepanocytosis. Subjects were 62 females and 52 males, with ages ranging from 22 to 82 years (median 46 years). 67 patients had undergone surgical splenectomy. Most patients (98 of 114) receive transfusions with filtered red blood cell concentrates (RBC) at regular intervals (mean 37 units of RBC transfused/year. Anti-SARS-CoV-2 virus antibody concentrations were determined by measuring the serum IgG neutralizing Ab levels against the RBD portion of the virus spike protein (anti-S). In the basal cohort, prior to the vaccination, 6 patients had SARS-CoV-2 (based on nucleic acid testing of pharyngeal swab samples). One patient resulted positive for basal IgG against SARS-CoV-2 nucleocapsid proteins. A finding of measurement above 7 binding antibody units (BAU) was considered correlated with protection against the SARS-CoV-2 virus. A p-value under 0.05 was considered significant for any correlation with factors predisposing to non-response. Results: The median value of serum anti-S IgG was 2184.4 BAU/mL [IQR 1127.4-3502.9]. All patients developed an IgG-neutralizing antibody level against the RBD portion of the spike protein superior to 7 BAU/mL (figures 1 and 2). The minimum measured value was 27.0 BAUI/mL. Only 9 patients reported a <500.0 BAUI/mL value (4 thalassemia intermedia, 3 thalassemia major, 2 thalasso-drepanocytosis). The patient with previous anti-N positivity showed an average IgG value of 2834.7 BAU/mL (29% above average). No differences were observed when patients were grouped by sex, age, types of hemoglobinopathy, transfusion-dependent disease or not, spleen status, iron chelation therapy, and use of other concurrent treatment (p>0.05). Patients’ baseline characteristics correlated with BAU are summarized in Table 1. Summary/Conclusion: Vaccination against SARS-CoV-2 has shown to be safe and immunogenic in thalassemia major and SCD patients. Additional studies are needed to assess the need and timing of booster vaccination or other prophylaxis drugs (e.g., tixagevimab-cilgavimab) to maintain long-term immunity and guarantee risk reduction.Keywords: COVID-19, Vaccination, Hemoglobinopathy